Acne vulgaris is a multifactorial disease with a seborrhoeic basis. Acne tends to appear during puberty and tends to fade away again, usually spontaneously when growth has stopped. Only rarely does it die away before the age of 20, and occasionally it is still to be found at the age of about 30. Since the face is one of the favorite locations affected and in severe cases the alterations give rise to considerable disfigurement, they have great aesthetic significance and they make it easy to comprehend the physical burden of the afflicted person.
Seborrhoea is a prerequisite for acne vulgaris. However, seborrhoea is certainly not the sole factor. In addition, there has to be a tendency toward the formation of follicular hyperkeratosis and, therefore, toward comedones. These formations, which are also called blackheads, represent plugs which close the excretory ducts of the sebaceous glands, i.e., the upper follicle excretory ducts, and mark the follicle ostia as dark spots.
The main foci of acne are the areas with an abundance of sebaceous glands, i.e., face, chest, neck and back.
For treating acne it is recommended to carry out a hot wash with Syndets. Following this a localized treatment is effected with, for example, sulphur, resorcinol, salicyclic acid, benzoyl peroxide or vitamin A acids.
All the known preparations have one or more disadvantages, e.g., lack of effectiveness. Accordingly, the cure rate with vitamin A acids is between 25 and 30%. This low success rate is due not only to the low stability of vitamin A acids but also to undesirable and distressing side effects.
The U.S. Pat. No. 4,021,572 discloses the use of lactic acid amides and quaternary ammonium lactates for the prevention and treatment of acne vulgaris.
The Belgian Patent Specification No. 753,823 discloses preparations for the localized treatment of acne vulgaris and seborrhoea, which contain a thio-ether of a 2-methyl-3-hydroxy-4-hydroxy-methylpyridine having the general formula: ##STR2## where R signifies an organic radical containing at least one amino group and, optionally, one carboxyl group. The carboxyl group may be esterified or amidated, whereas the amino group is present either in the form of a salt of an inorganic or organic acid, or may be substituted by an acyl group or sulphonyl group or one or two optionally substituted alkyl radicals.
Finally, the French Patent Specification No. 2,308,354 relates to a preparation for the localized treatment of acne and containing benzaldehyde as the active substance.
After exhaustive research into the pharmacological properties of pyridine aldehydes, it has surprisingly been found that pyridine aldehydes, particularly pyridine-3-aldehyde, in concentrations of from 0.05 to 5% by weight, preferably 0.1 to 3% by weight, can cure acne vulgaris within a short time and can also improve the appearance of the skin as well as cleansing it thoroughly.
The invention is thus based on the object of making available preparations containing pyridine aldehydes, in particular pyridine-3-aldehyde, for the localized treatment of acne vulgaris. A further object of the invention is to develop a method for the localized treatment of acne vulgaris, in which a pyridine aldehyde, preferably a pyridine-3-aldehyde, is used as the active substance.
The expression `localized treatment of acne vulgaris` means the prophylaxis and therapy of the skin of a person who is prone to acne vulgaris or who is suffering from acne vulgaris.
The pyridine aldehydes used according to the invention have the formula: ##STR3## where n has the value 0 or 1. The aldehyde group is in the 2-, 3- or 4-position and the methyl group in the 2- or 6-position. Particular examples of pyridine aldehydes which can be used according to the invention are pyridine-2-aldehyde, pyridine-3-aldehyde, 2-methyl pyridine-3-aldehyde, 6-methyl pyridine-2-aldehyde and pyridine-4-aldehyde. Pyridine-3-aldehyde is particularly preferred. Accordingly, the invention will be described below with reference to this compound. These pyridine aldehydes are known and can be produced easily according to conventional processes.
The mechanism of the action of pyridine aldehydes in the invention and treatment of acne vulgaris is not yet known.
Suitable preparations, according to the invention, for the prevention and treatment of acne vulgaris are, for example, aqueous alcoholic solutions, and solutions in alcohols, polyglycols, lactic acid esters, phenylalkanols such as benzyl alcohol or phenyl ethanol or mixtures thereof. Special examples of alcohols which can be used are ethanol, propanol and propylene glycol. The preparations may contain additives, such as ethereal oils, azulene oils or conifer oils. Lactic acid ethyl ester may be incorporated into the liquid preparations as an antioxidant. It is preferable to add lactic acid ethyl ester in a quantity of from 5 to 40% by weight. The addition of glycerine or polyethylene glycol results in preparations which keep the skin moist and smooth. Ointments, creams, jellies and lotions may also incorporate the pyridine aldehydes, optionally together with preservatives, such a butylated hydroxy toluene or tocopherols.
According to the concentration of pyridine aldehyde, within the first few minutes after applying the preparations to the skin, reddening and warming of the skin region takes place. This effect lasts for approximately one hour. After several days of applying the solutions, jellies, lotions, creams or powders, the complexion of the normally markedly pallid juvenile acne sufferer becomes pleasantly ruddy and of healthy appearance. The preparations are applied two or three times a week to the skin so as to ensure the healing action.
Under the treatment with the pyridine aldehydes used according to the invention, within a few days, in persistent cases at latest after four to six weeks, the blackheads, pustules and pus-foci disappear. The skin is improved in appearance, the paleness diminishes and the large undesirable skin pores contract to normal size. Such an effect is not found in any of the known acne-treating agents.